499 lines
14 KiB
C++
499 lines
14 KiB
C++
/* mbed Microcontroller Library
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* Copyright (c) 2006-2012 ARM Limited
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/* Introduction
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* ------------
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* SD and MMC cards support a number of interfaces, but common to them all
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* is one based on SPI. This is the one I'm implmenting because it means
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* it is much more portable even though not so performant, and we already
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* have the mbed SPI Interface!
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*
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* The main reference I'm using is Chapter 7, "SPI Mode" of:
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* http://www.sdcard.org/developers/tech/sdcard/pls/Simplified_Physical_Layer_Spec.pdf
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*
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* SPI Startup
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* -----------
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* The SD card powers up in SD mode. The SPI interface mode is selected by
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* asserting CS low and sending the reset command (CMD0). The card will
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* respond with a (R1) response.
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*
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* CMD8 is optionally sent to determine the voltage range supported, and
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* indirectly determine whether it is a version 1.x SD/non-SD card or
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* version 2.x. I'll just ignore this for now.
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*
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* ACMD41 is repeatedly issued to initialise the card, until "in idle"
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* (bit 0) of the R1 response goes to '0', indicating it is initialised.
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*
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* You should also indicate whether the host supports High Capicity cards,
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* and check whether the card is high capacity - i'll also ignore this
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*
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* SPI Protocol
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* ------------
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* The SD SPI protocol is based on transactions made up of 8-bit words, with
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* the host starting every bus transaction by asserting the CS signal low. The
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* card always responds to commands, data blocks and errors.
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*
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* The protocol supports a CRC, but by default it is off (except for the
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* first reset CMD0, where the CRC can just be pre-calculated, and CMD8)
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* I'll leave the CRC off I think!
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*
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* Standard capacity cards have variable data block sizes, whereas High
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* Capacity cards fix the size of data block to 512 bytes. I'll therefore
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* just always use the Standard Capacity cards with a block size of 512 bytes.
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* This is set with CMD16.
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*
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* You can read and write single blocks (CMD17, CMD25) or multiple blocks
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* (CMD18, CMD25). For simplicity, I'll just use single block accesses. When
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* the card gets a read command, it responds with a response token, and then
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* a data token or an error.
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*
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* SPI Command Format
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* ------------------
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* Commands are 6-bytes long, containing the command, 32-bit argument, and CRC.
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*
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* +---------------+------------+------------+-----------+----------+--------------+
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* | 01 | cmd[5:0] | arg[31:24] | arg[23:16] | arg[15:8] | arg[7:0] | crc[6:0] | 1 |
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* +---------------+------------+------------+-----------+----------+--------------+
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*
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* As I'm not using CRC, I can fix that byte to what is needed for CMD0 (0x95)
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*
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* All Application Specific commands shall be preceded with APP_CMD (CMD55).
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*
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* SPI Response Format
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* -------------------
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* The main response format (R1) is a status byte (normally zero). Key flags:
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* idle - 1 if the card is in an idle state/initialising
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* cmd - 1 if an illegal command code was detected
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*
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* +-------------------------------------------------+
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* R1 | 0 | arg | addr | seq | crc | cmd | erase | idle |
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* +-------------------------------------------------+
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*
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* R1b is the same, except it is followed by a busy signal (zeros) until
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* the first non-zero byte when it is ready again.
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*
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* Data Response Token
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* -------------------
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* Every data block written to the card is acknowledged by a byte
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* response token
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*
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* +----------------------+
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* | xxx | 0 | status | 1 |
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* +----------------------+
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* 010 - OK!
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* 101 - CRC Error
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* 110 - Write Error
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*
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* Single Block Read and Write
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* ---------------------------
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*
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* Block transfers have a byte header, followed by the data, followed
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* by a 16-bit CRC. In our case, the data will always be 512 bytes.
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*
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* +------+---------+---------+- - - -+---------+-----------+----------+
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* | 0xFE | data[0] | data[1] | | data[n] | crc[15:8] | crc[7:0] |
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* +------+---------+---------+- - - -+---------+-----------+----------+
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*/
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#include "SDFileSystem.h"
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#include "mbed_debug.h"
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#define SD_COMMAND_TIMEOUT 5000
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#define SD_DBG 0
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SDFileSystem::SDFileSystem(PinName mosi, PinName miso, PinName sclk, PinName cs, const char* name) :
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FATFileSystem(name), _spi(mosi, miso, sclk), _cs(cs), _is_initialized(0) {
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_cs = 1;
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// Set default to 100kHz for initialisation and 1MHz for data transfer
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_init_sck = 100000;
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_transfer_sck = 1000000;
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}
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#define R1_IDLE_STATE (1 << 0)
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#define R1_ERASE_RESET (1 << 1)
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#define R1_ILLEGAL_COMMAND (1 << 2)
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#define R1_COM_CRC_ERROR (1 << 3)
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#define R1_ERASE_SEQUENCE_ERROR (1 << 4)
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#define R1_ADDRESS_ERROR (1 << 5)
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#define R1_PARAMETER_ERROR (1 << 6)
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// Types
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// - v1.x Standard Capacity
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// - v2.x Standard Capacity
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// - v2.x High Capacity
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// - Not recognised as an SD Card
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#define SDCARD_FAIL 0
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#define SDCARD_V1 1
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#define SDCARD_V2 2
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#define SDCARD_V2HC 3
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int SDFileSystem::initialise_card() {
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// Set to SCK for initialisation, and clock card with cs = 1
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_spi.frequency(_init_sck);
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_cs = 1;
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for (int i = 0; i < 16; i++) {
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_spi.write(0xFF);
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}
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// send CMD0, should return with all zeros except IDLE STATE set (bit 0)
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if (_cmd(0, 0) != R1_IDLE_STATE) {
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debug("No disk, or could not put SD card in to SPI idle state\n");
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return SDCARD_FAIL;
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}
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// send CMD8 to determine whther it is ver 2.x
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int r = _cmd8();
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if (r == R1_IDLE_STATE) {
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return initialise_card_v2();
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} else if (r == (R1_IDLE_STATE | R1_ILLEGAL_COMMAND)) {
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return initialise_card_v1();
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} else {
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debug("Not in idle state after sending CMD8 (not an SD card?)\n");
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return SDCARD_FAIL;
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}
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}
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int SDFileSystem::initialise_card_v1() {
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for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
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_cmd(55, 0);
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if (_cmd(41, 0) == 0) {
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cdv = 512;
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debug_if(SD_DBG, "\n\rInit: SEDCARD_V1\n\r");
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return SDCARD_V1;
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}
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}
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debug("Timeout waiting for v1.x card\n");
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return SDCARD_FAIL;
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}
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int SDFileSystem::initialise_card_v2() {
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for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
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wait_ms(50);
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_cmd58();
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_cmd(55, 0);
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if (_cmd(41, 0x40000000) == 0) {
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_cmd58();
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debug_if(SD_DBG, "\n\rInit: SDCARD_V2\n\r");
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cdv = 1;
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return SDCARD_V2;
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}
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}
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debug("Timeout waiting for v2.x card\n");
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return SDCARD_FAIL;
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}
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int SDFileSystem::disk_initialize() {
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_is_initialized = initialise_card();
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if (_is_initialized == 0) {
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debug("Fail to initialize card\n");
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return 1;
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}
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debug_if(SD_DBG, "init card = %d\n", _is_initialized);
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_sectors = _sd_sectors();
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// Set block length to 512 (CMD16)
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if (_cmd(16, 512) != 0) {
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debug("Set 512-byte block timed out\n");
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return 1;
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}
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// Set SCK for data transfer
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_spi.frequency(_transfer_sck);
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return 0;
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}
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int SDFileSystem::disk_write(const uint8_t* buffer, uint64_t block_number, uint8_t count) {
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if (!_is_initialized) {
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return -1;
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}
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for (uint64_t b = block_number; b < block_number + count; b++) {
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// set write address for single block (CMD24)
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if (_cmd(24, b * cdv) != 0) {
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return 1;
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}
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// send the data block
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_write(buffer, 512);
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buffer += 512;
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}
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return 0;
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}
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int SDFileSystem::disk_read(uint8_t* buffer, uint64_t block_number, uint8_t count) {
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if (!_is_initialized) {
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return -1;
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}
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for (uint64_t b = block_number; b < block_number + count; b++) {
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// set read address for single block (CMD17)
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if (_cmd(17, b * cdv) != 0) {
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return 1;
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}
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// receive the data
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_read(buffer, 512);
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buffer += 512;
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}
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return 0;
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}
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int SDFileSystem::disk_status() {
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// FATFileSystem::disk_status() returns 0 when initialized
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if (_is_initialized) {
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return 0;
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} else {
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return 1;
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}
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}
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int SDFileSystem::disk_sync() { return 0; }
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uint64_t SDFileSystem::disk_sectors() { return _sectors; }
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// PRIVATE FUNCTIONS
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int SDFileSystem::_cmd(int cmd, int arg) {
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_cs = 0;
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// send a command
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_spi.write(0x40 | cmd);
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_spi.write(arg >> 24);
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_spi.write(arg >> 16);
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_spi.write(arg >> 8);
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_spi.write(arg >> 0);
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_spi.write(0x95);
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// wait for the repsonse (response[7] == 0)
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for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
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int response = _spi.write(0xFF);
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if (!(response & 0x80)) {
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_cs = 1;
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_spi.write(0xFF);
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return response;
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}
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}
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_cs = 1;
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_spi.write(0xFF);
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return -1; // timeout
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}
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int SDFileSystem::_cmdx(int cmd, int arg) {
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_cs = 0;
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// send a command
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_spi.write(0x40 | cmd);
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_spi.write(arg >> 24);
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_spi.write(arg >> 16);
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_spi.write(arg >> 8);
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_spi.write(arg >> 0);
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_spi.write(0x95);
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// wait for the repsonse (response[7] == 0)
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for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
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int response = _spi.write(0xFF);
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if (!(response & 0x80)) {
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return response;
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}
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}
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_cs = 1;
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_spi.write(0xFF);
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return -1; // timeout
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}
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int SDFileSystem::_cmd58() {
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_cs = 0;
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int arg = 0;
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// send a command
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_spi.write(0x40 | 58);
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_spi.write(arg >> 24);
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_spi.write(arg >> 16);
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_spi.write(arg >> 8);
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_spi.write(arg >> 0);
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_spi.write(0x95);
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// wait for the repsonse (response[7] == 0)
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for (int i = 0; i < SD_COMMAND_TIMEOUT; i++) {
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int response = _spi.write(0xFF);
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if (!(response & 0x80)) {
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int ocr = _spi.write(0xFF) << 24;
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ocr |= _spi.write(0xFF) << 16;
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ocr |= _spi.write(0xFF) << 8;
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ocr |= _spi.write(0xFF) << 0;
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_cs = 1;
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_spi.write(0xFF);
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return response;
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}
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}
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_cs = 1;
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_spi.write(0xFF);
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return -1; // timeout
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}
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int SDFileSystem::_cmd8() {
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_cs = 0;
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// send a command
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_spi.write(0x40 | 8); // CMD8
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_spi.write(0x00); // reserved
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_spi.write(0x00); // reserved
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_spi.write(0x01); // 3.3v
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_spi.write(0xAA); // check pattern
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_spi.write(0x87); // crc
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// wait for the repsonse (response[7] == 0)
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for (int i = 0; i < SD_COMMAND_TIMEOUT * 1000; i++) {
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char response[5];
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response[0] = _spi.write(0xFF);
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if (!(response[0] & 0x80)) {
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for (int j = 1; j < 5; j++) {
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response[i] = _spi.write(0xFF);
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}
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_cs = 1;
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_spi.write(0xFF);
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return response[0];
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}
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}
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_cs = 1;
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_spi.write(0xFF);
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return -1; // timeout
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}
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int SDFileSystem::_read(uint8_t *buffer, uint32_t length) {
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_cs = 0;
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// read until start byte (0xFF)
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while (_spi.write(0xFF) != 0xFE);
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// read data
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for (uint32_t i = 0; i < length; i++) {
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buffer[i] = _spi.write(0xFF);
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}
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_spi.write(0xFF); // checksum
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_spi.write(0xFF);
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_cs = 1;
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_spi.write(0xFF);
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return 0;
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}
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int SDFileSystem::_write(const uint8_t*buffer, uint32_t length) {
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_cs = 0;
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// indicate start of block
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_spi.write(0xFE);
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// write the data
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for (uint32_t i = 0; i < length; i++) {
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_spi.write(buffer[i]);
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}
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// write the checksum
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_spi.write(0xFF);
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_spi.write(0xFF);
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// check the response token
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if ((_spi.write(0xFF) & 0x1F) != 0x05) {
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_cs = 1;
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_spi.write(0xFF);
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return 1;
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}
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// wait for write to finish
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while (_spi.write(0xFF) == 0);
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_cs = 1;
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_spi.write(0xFF);
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return 0;
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}
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static uint32_t ext_bits(unsigned char *data, int msb, int lsb) {
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uint32_t bits = 0;
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uint32_t size = 1 + msb - lsb;
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for (uint32_t i = 0; i < size; i++) {
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uint32_t position = lsb + i;
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uint32_t byte = 15 - (position >> 3);
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uint32_t bit = position & 0x7;
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uint32_t value = (data[byte] >> bit) & 1;
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bits |= value << i;
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}
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return bits;
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}
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uint64_t SDFileSystem::_sd_sectors() {
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uint32_t c_size, c_size_mult, read_bl_len;
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uint32_t block_len, mult, blocknr, capacity;
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uint32_t hc_c_size;
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uint64_t blocks;
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// CMD9, Response R2 (R1 byte + 16-byte block read)
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if (_cmdx(9, 0) != 0) {
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debug("Didn't get a response from the disk\n");
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return 0;
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}
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uint8_t csd[16];
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if (_read(csd, 16) != 0) {
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debug("Couldn't read csd response from disk\n");
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return 0;
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}
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// csd_structure : csd[127:126]
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// c_size : csd[73:62]
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// c_size_mult : csd[49:47]
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// read_bl_len : csd[83:80] - the *maximum* read block length
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int csd_structure = ext_bits(csd, 127, 126);
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switch (csd_structure) {
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case 0:
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cdv = 512;
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c_size = ext_bits(csd, 73, 62);
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c_size_mult = ext_bits(csd, 49, 47);
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read_bl_len = ext_bits(csd, 83, 80);
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block_len = 1 << read_bl_len;
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mult = 1 << (c_size_mult + 2);
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blocknr = (c_size + 1) * mult;
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capacity = blocknr * block_len;
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blocks = capacity / 512;
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debug_if(SD_DBG, "\n\rSDCard\n\rc_size: %d \n\rcapacity: %ld \n\rsectors: %lld\n\r", c_size, capacity, blocks);
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break;
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case 1:
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cdv = 1;
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hc_c_size = ext_bits(csd, 63, 48);
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blocks = (hc_c_size+1)*1024;
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debug_if(SD_DBG, "\n\rSDHC Card \n\rhc_c_size: %d\n\rcapacity: %lld \n\rsectors: %lld\n\r", hc_c_size, blocks*512, blocks);
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break;
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default:
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debug("CSD struct unsupported\r\n");
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return 0;
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};
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return blocks;
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}
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